Abstract: The oil and gas structures at Longquan Mountains have the full combination including generation, reservoir and cap rock. The Jurassic and Cretaceous are non-coal strata. There are seven structural heights and jointed fracture zones which are favorable to gather shallow gas. The sandstone of Shaximiao formation is the primary reservoir of the shallow gas. It is so easy to generate engineering accidents when tunneling across the layer. The tunneling would be harmed by enriched shallow gas. There are three lines including the east extension of Cheng-Luo highway, the Cheng-An-Yu expressway and the Cheng-Yu railway. The analyses of gas concentrations that come from twenty drillings of eight tunnels show that the eight tunnels have gas presence. The highest gas concentration is 8.654% and the lowest gas concentration is 0.081%,which reveal that the eight tunnels have been affected by the gas. The present study has found that the main influencing factors of the tunnels are structure location and rock properties. Tunneling would be harmed when it is near the high point of oil and gas structures or passes the fractured formations with high concentration gas.